Libera Me
by Ayien
Summary: An occult detective and a vigilante meet on a dark night in Gotham. A crossover with Constantine.


**A/N:** Written for Yuletide. Contains references to Christian theology.

* * *

The Narrows stink.

John slouches down the street, past open air bars full of cheap booze and even cheaper women, his Amityville Screech Beetle rattling in its box in the pocket of his coat. The bartender is a half-demon, his eyes gleaming dirty-red, and he smiles at John, raises his shotglass in a mocking salute, before turning back to draw more fools into his embrace.

John sneers at him. Everyone- Heaven, Hell- is waiting for him to fall again.

He steps over tainted needles, broken glass sparkling in the dim half-light of Gotham, Nicorette gum bitter on his tongue.

He _hates_ Gotham.

It's a city rotting from the inside out, infected with a cancer of the soul, and he wonders as he glances up at a street-sign with 'Fuck Batman' sloppily painted over it if God has forgotten this place.

The Holy Nail is heavy in his pocket.

Something rustles in the shadows of the alleyway, and he turns to see dark eyes gleam as a man robed in darkness steps out of the gloom. A tall man, not bulky even wrapped in Kevlar plating; just dangerous. His eyes are the overly-bright eyes of the sick.

How nice. Gotham's vigilante psychopath is here to welcome him.

"You shouldn't be wandering around in the Narrows, Mr… ?"

"Constantine," John says. He probably should have thrown his first name in, too, since his name's a pretty uncommon one and it's not like it's impossible to find him with just his last name.

He blinks, focusing on the Batman with all of his senses, not just sight.

The Batman fairly _glows_ with purpose, in a way that John has not seen on anyone except the strange man in Metropolis, a faint white aura leeching the color from the world around him. Not even a God-given purpose; not holy nor demonic.

A human purpose.

Batman's lips twitch, curl in something very like a smile, his voice, the raspy voice of someone who has spent far too long breathing in the stench of corruption, low as he says,

"Constantine." The name falls from his lips like a stone dropping into a crevasse, lingers like smoke off a cigarette.

In all honesty, the voice is a little over-the-top, but he's not going to tell that to a guy who's become famous for dangling mobsters off buildings and kidnapping businessmen from Hong Kong.

"What are you doing here?" Batman prowls closer, like a wolf, threatening in his very existence. John turns on his heel, keeping him in sight. If the man wants to be intimidating, he's doing a very good job of it.

"I'm here to find a guy and stab him with this." He holds out the Nail on his palm.

Batman tilts his head in question. "And that is?"

John holds it up to the light. It is still new, untarnished, sparkles. He can _feel_ Batman's regard, a sharp focus almost animalistic in its intensity.

The blood smeared on the nail and the rags of flesh are still as bright as the day they were ripped from his feet. He turns it in his fingers, and wonders why he feels so disappointed in its simplicity- its humanity. "This is one of the three Holy Nails torn from the flesh of Jesus Christ. The Vatican's probably going to be demanding its return any day now."

"You stole that from the _Vatican?_"

"No; they're paying me to hunt down a Fallen that's been running around on Earth and send him back. Lent me this to do the job."

"You're an exorcist?"

John rolls his eyes. "Occult detective, actually."

Batman's lip curls as he scoffs, taking another step closer. "Great. I always get the crazy ones."

"If you don't believe me, that's fine, but I wouldn't come any closer."

The other man stops, a hulking shadow against the flickering light of the streetlamp outside. "And why not?"

"I could paralyze you with a cantrip and leave you down here for the scum to feast on," John offers, "but I'm pretty sure that's not how you want to spend your Sunday night. And-" he jerks back as Batman feints, "I _really_ wouldn't do that. It's not exactly endearing you to me."

Batman pauses, weighing the situation, then seems to decide that he might as well play into his delusions.

Whatever; as long as he doesn't interfere, John doesn't have too much of a problem with him tagging alone.

"So, what's a Fallen?" His voice is amused, tolerant.

John glances down the street, feeling exposed, the fact that any drug dealer could take a shot at him out in the open and he wouldn't be able to stop it prickling icy-cold down his spine.

Fuck it.

He joins Batman in the shadows of the alley, swallowing as a rat as big as his foot scuttles by, naked tail flashing white in the gloom.

"A Fallen is a fallen angel. This one's known as Abaddon."

Batman moves, an indrawn breath hissing between them. It sounds like the last breath of a dying man. "Abaddon? From Revelations?"

"Yeah. I'm surprised you know him: most people tend to ignore the New Testament books that aren't Gospels." It'd be hilarious if the Batman was a priest in daily life; hilarious in a sick, demented way.

The best kind of hilarity.

Batman ignores the invitation to speak.

This man has no social skills at all.

Constantine shrugs. "The problem with Abaddon is that Abaddon's not his real name. In the Greek, he's known as Apollyon, also known as the Destroyer. He's so powerful that you can't use any relic to exorcise him: it's got to be either a Holy Nail, a fragment of the True Cross, or a piece of the Crown of Thorns." He shrugs. "They didn't trust me with the Cross or the Crown, so I got a piece of metal."

Batman doesn't move.

"Abaddon's one of the more powerful demons walking around, but he's possessed a junkie by the name of- excuse me a moment." He fishes in his pocket for the scrap of paper his half-angel contact gave him, deciphering his own scrawl. "He's in some junkie named Robert Matheson. I asked around the Narrows and found out that poor Robert's been having issues getting high. Seems like Abaddon doesn't like his hosts screwing with his body."

"Do you know where Matheson is?" Batman leans forward out of the shadows, Kevlar-plated fists creaking as he uncurls his fingers.

Jesus. You could cut rock on the guy's jawline.

"He usually panhandles around 32nd, according to my source."

Batman's mouth flattens into a thin line as he jerks his chin to the left. "Two streets that way."

"Thanks." John slips the nail back into his pocket and starts off, coat flapping in the wind off the river, Batman a silent, brooding presence at his side, like a shape cut out of starless night. He'd be annoyed at the other man appointing himself his babysitter, but this _is _Gotham, and having somebody by his side is worth the annoyance. The smell of vomit and pot and blood seeps along the ground like a miasma, but Batman looks comfortable here.

But he would-

This is, after all, his city.

"What will happen to Matheson after you… exorcise him?"

Nothing good.

"If Matheson's been shooting up over and over trying to get a fix, the minute Abaddon leaves him, everything that Abaddon held back will happen to him. So he'll basically just die within a minute from a massive cocaine overdose. But lucky for him, I'm putting him on an expressway to Heaven." He tries to smile and knows he's failed.

Batman glances sidelong at him, eyes bright within the shadow of black grease paint. "There's no way to save him?"

"Not unless you've got some way to neutralize several hundred doses of cocaine in the space of a minute. And if you want me to hold off on the exorcism, tough luck, because the longer Abaddon stays, the worse the Narrows are going to get."

Batman's jaw clenches, but he says nothing but "32nd."

Abandoned buildings glare down at them, boarded-up windows splattered with graffiti. A car streaked with dust, paint peeling off the body, rests on blocks in the middle of the intersection, an inconvenience to everyone.

He feels Abaddon's presence, a thick, choking black stench that makes his eyes water and the hair on his arms prickle. Staggers, bile rising in his throat.

"Constantine?" Batman catches him with a hand beneath his elbow, bearing him up.

"In that alley," he croaks, nodding in the direction of a black space between an old barbershop and a derelict corner grocery. As Batman hauls him toward the demon, he pulls out the Holy Nail.

It glows white from within, a pure, bright light in the darkness. Batman stares at it for a long moment before making a rough noise of discontent, obviously skeeved out by the evidence glowing in his face of demons and magic.

Something rattles in the shadows.

"Constantine," Abaddon says in a voice that sounds like someone calling from the depths of the pit. "Hast thou come to cast me out?"

"Great. One of the melodramatic demons," John mutters as he holds the Nail high.

Its light illuminates Matheson, who lies on his back beside some trash cans, twitching, his skin starting to burn in the light of the Nail. His tattered black coat lies beside him, bundled into a pillow. Matheson rolls his head to the side in a way that no human could do, and Batman tenses at the sight of his eyes gleaming red as flame, a serpent's tongue falling from his half-open mouth.

"Your relic of the False Savior cannot harm me," Abaddon hisses, rising to his knees.

"Really?" John says, and takes a threatening step, shoving the Nail closer. Abaddon recoils, flings a hand pockmarked with injection sites up, and falls back as the light pours over him, spasming like an epileptic on the ground, his spine arching, snapping down like a rubber band.

"Constantine-" Batman begins, only to fall silent as John snaps, "Hold his feet!"

The other man grabs Abaddon's feet, pinning him as John straddles his pelvis, wrinkling his nose. It smells like Matheson hadn't bathed in weeks, and he ignores the suspicious stains all over Matheson's clothing with a herculean effort as he unbuttons the parka and undershirt.

Abaddon bucks beneath him, snarling Aramaic and Hebrew curses as John cuts the sign of the cross into the skin above Matheson's heart with the tip of the Nail, red, raised lines following every stroke as he mutters,

"Depart, then, transgressor. Depart, seducer, full of lies and cunning, foe of virtue, persecutor of the innocent. Give place, abominable-"

A howl like no earthly beast could produce rings off the buildings as Matheson arches beneath him, bleeding off demonic energy like a black cloud, Abaddon's parting snarl making Batman flinch.

John doesn't, and nurses a secret pride in his heart that here there is something he knows, and Batman doesn't.

Abaddon departs in a ring of thunder, unable to stand the power of one of the holiest relics in the world, in a flash of sulfur and shadow, leaving only a man behind.

Matheson blinks clouded eyes, smiles in gratitude, and it is all John can do not to smile back.

Because he doesn't deserve gratitude, and- ah, there he goes.

Matheson grabs onto John's arms with shaking fingers, his yellowed nails digging into his skin with every spasm, his eyes black with internal bleeding as all the damage Abaddon held back comes crashing in on him, a cascade of needle holes and bruises washing over his skin like rain.

He gurgles, spits up blood reeking of poison, the blood dribbling down his chin, streaking red over his tattered parka.

"It's okay," John whispers. The man's eyes roll, focus blearily on him. John sketches the cross in the air above him, mutters, "In paradisum deducant te Angeli; in tuo adventu suscipiant te Martyres, et perducant…"

He realizes halfway through the prayer that another voice is accompanying him.

Huh.

Apparently Batman's a Catholic.

The man coughs, shudders, relaxes, head falling back with a limpness that can't be mistaken for anything but death.

John lets him slide to the ground, covers his face with his tattered coat as he slips the Nail into the pocket of his own coat, and turns to see Batman staring down at the dead Matheson.

His eyes are pits of wounded grief, his shoulders shuddering once, and then no more.

And John realizes that this man's obsession with Gotham extends to its people as well.

He's fucking grateful that he will never know what it is to mourn every death.

"When do you plan to leave?" Batman says as he tears his gaze away from the shapeless form beneath the cloth.

John glances at his watch.

Fuck. It's almost three in the morning, and his flight's in two and a half hours- he can make it to the airport, but it's going to be tight.

"Now. I need to have the Nail back by Tuesday."

Batman nods slowly, then stares at him with unnerving consideration. "Good. I can't say I enjoyed the experience, but it was certainly… memorable."

"They tend to be."

Batman almost smiles. "Thanks for helping my city."

John shrugs, stares down at the paper-skinned fingers spread across the pavement. "It was the least I could do." He brushes the clinging dust of the street off on his pants and turns, sticking his hands in his pockets and striding down the alley into the light.

No goodbyes; something tells him Batman's not the type.

Something makes him stop, turn in time to see Batman lift the dead man's arm and place it beneath the coat, hiding his frailty from the world, before disappearing into shadow, cape flickering like Gabriel's lost wings for a moment before it is gone.

Swallowed up in death and darkness.

He roots in his pocket for the Nail, holds it up to the light. The blood gleams ruby.

Two thousand years ago a man died a human death on Golgotha to save the world, to fulfill a divine purpose.

Today a man dies another death every night to save a city that can't be saved.

Because he, too, has his own purpose.

John holds the Nail up, glances from it to the spot where Batman stood only a moment ago, and he wonders which is the greater sacrifice.

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**A/N:** Comments and criticism are always loved.


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